Dr Andrea D Székely

THE ANATOMY OF THE ENDOCRINE SYSTEM I.Hypophysis and epiphysis

HYPOPHYSIS

PITUITARY GLAND - small, smooth surface, round or oval dorsoventrally flattened szerv.

stalk: infundibulum behind the chiasma opticum; hypophyseal

fossa, basilar venous sinusoid system surrounds it

,. diaphragma sellae, dural duplication, foramen diaphragmaticum.

MORPHOLOGYHYPOPHYSISADENOHYPOPHYSIS (anterior lobe)

1. pars tuberalis (pars proximalis) covers the stalk of the gland,

2. pars intermedia (intermediate lobe) is immediately in front of the posterior lobe,

3. pars distalis (pharyngeal part) largest division.

NEUROPHYPOPHYSIS (posterior lobe):

1. pars proximalis (pars infundibularis)

2. pars distalis neurohypophysis.

HYPOPHYSIS FUNCTION

HYPOPHYSIS HORMONES

TOPOGRAPHY AND BLOOD SUPPLYHYPOPHYSIS15–20 small branches of the circulus arteriosus Willisii (from the internal carotid) (ant and post hypophysial branches)

Venous drainage: circular sinus or the a cavernosus sinus

The portal system is supplied by the rostral hypophyseal aa. branching within the infundibular part. The portal veins (venous capillaries) supply the major part of the anterior lobe. They form sinusoids then merge and are drained by the dural sinuses.

Perivascular sympathetic vasomotor axons supply the gland, they derive from the internal carotid plexus, and the hypothalamus; innervate the vessels and the acini.

ANTERIOR LOBE HISTOLOGYHYPOPHYSISBundles of rounded cells are surrounded by CT and the sinusoidal system, every cell is in contact with the fenestrated endothelium.

Somatic or satellite cells are between the bundles.The glandular cells contain granules , prohormones. acidophil alpha-cells (40%), basophil beta-cells (10%) chromophob c-cells (50%)

Immunhistochemistry reveales hormones, releasing factors or liberins – accordingly:somatotrop (STH), lactotrop (LTH), gonadotrop (GNRH) luteotrop (LH), thyreotrop (TSH), and corticotrop (ACTH) cells are distinguished.

There is a functional difference in the number of cell groups depending on age, gender, status (pregnancy, lactation etc).

Sometimes the cells form a syntitium (symplasma). Holocrin secretion will kill the cells. Degranulation (complete) will lead to the presence of chromophob cells.

HYPOPHYSIS ANTERIOR LOBE HISTOLOGY

Pars tuberalis

Vasopressin V1B receptor expression

In the intermediate lobe, the majority of the cells are basophil, small follicles are formed. EM studies revealed several cell types.

Characteristic secret - melanotropin (MSH), enhances the level of melanin in amphibia (within the melanophor cells). In certain species, they poduces lipotropin, to liberate lipids.

HYPOPHYSIS IM LOBE HISTOLOGY

The neurohypophysis is neural tissue wither a poorer vascular network and fine CT framework, with axons and supporting cells (pituicytes).

Sometimes there is a basophil infitration from the IM lobe, and with age the cells may contain pigmentation (intra- and extracellular).

NO HORMON PRODUCTION but the hypothalamic nuclei (nucleus supraopticus, nucleus paraventricularis) send their axons here. The synaptic vesicles contain antidiuretic hormon (ADH; vasopressin) and oxytocin; the axon terminals are enlarged (Hering bodies), they are emptied through axovasal synapses into the blood.

POSTERIOR LOBE HISTOLOGYHYPOPHYSIS

DEVELOPMENTHYPOPHYSISIt derives from two primordia.

The pharyngeal Rathke pouch, and the protrusion (processus infundibuli) of the basal plate of the diencephalon.

Rathke derivatives: anterior wall – anterior lobe, posterior wall- intermediate lobe

The processus infundibuli gives rise to the neurohypophysis. It contains the infundibular recess of the 3rd ventricle.

PATHOLOGYHYPOPHYSISADENOMA

TYPES:       Prolactinoma (prolactin excess )       GH adenoma       TSH adenoma       ACTH adenoma       LH-FSH adenoma       Hormonally inactive pituitary tumors

gigantism

akromegália

Compresses the optic chiasm

Dislocates the artery

Compresses the hypophysis

Changes the shape of the sinus

Transsphenoidal endoscopic surgery

A fat graft is placed in the area where the tumor was removed. A cartilage graft is placed to close the hole in the sella. Biologic glue is applied over the area

PITUITARY TUMOR SURGERY

EPIPHYSISThe pineal gland is a small and reddish brown, compact organ located at the top ofthe 3rd ventricle close to the superior colliculi. The habenula connects it to the diencephalon. It contains the pineal recess.

Capsule: CT and glial cells, develops from the soft meninges. The CT septa contain a rich vascular supply forming small divisions within the parenchyma. The framework of the parenchyma is a vascular-glial network. The glandular cells derive from glial cells.

SECRETUM: melatonin , it liberates GH and so furthers sexual maturation. It is connected to the biological rythm system, the hormon production is regulated by the incoming light.

The pineal gland receives a sympathetic innervation from the superior cervical ganglion. However, a parasympathetic innervation from the sphenopalatine and otic ganglia is also present. Further, some nerve fibers penetrate into the pineal gland via the pineal stalk (central innervation). Finally, neurons in the trigeminal ganglion innervate the gland with nerve fibers containing the neuropeptide, PACAP. Human follicles contain a variable quantity of gritty material, called corpora arenacea (or "acervuli," or "brain sand"). Chemical analysis shows that they are composed of calcium phosphate, calcium carbonate, magnesium phosphate, and ammonium phosphate. In 2002, deposits of the calcite form of calcium carbonate were described. Calcium, phosphorus and fluoride deposits in the pineal gland have been linked with aging.

MORPHOLOGY TOPOGRAPHY

EPIPHYSIS Small molecules Peptides

5-methoxytryptophol Arginine vasotocinAdrenaline Angiotensin I

NoradrenalineMelano-und lipotropinsSerotonin Enkephalins

HistamineInositol

Iodinated compoundsTaurine

Pteridines

PRODUCES:

FUNCTIONEPIPHYSIS

HISTOLOGYEPIPHYSIS

Pinealocytes or chief cells, poligonal, with processes, rich in cytoplasm, melatoninsynthesis. Some of them show signs of involution (degeneration). They produce cysts, a calcium or magnesium salts containing concrements, granules (acervuli cerebri).

Astrocytes have a fibrous cytoplasm; sparsed in groups. In the border of the lobules sometimes a loose network of gliocytes is visible (gliaplaque) where no pinealocytes are to be seen.

The cysts and the pineal recess is lined with ependymal cells.

Occasional mast cells.

DEVELOPMENTEPIPHYSIS

The pineal body develops from the caudodorsal protrusion of the diencephalon. The soft meninges will wrap it completely then an arterial bud of the plexus chorioideus ventriculi tertii starts growing in, and then the pineal recessus forms. It is the remainder of the stalk of the ancient 3rd, parietal eye of some reptiles..

PATHOLOGY

All tumors involving the pineal gland are rare; most (50% to 70%) arise from sequestered embryonic germ cells. They most commonly take the form of so-called germinomas, resembling testicular seminoma or ovarian dysegerminoma. Other lines of germ cell differentiation include embryonal carcinomas; choriocariconmas; mixtures of germinom, embryonal carcinoma, and choriocarcinoma; and , uncommonly, typical teratomas (usually benign). Whether to charcterize these germ cell neoplasms as pinealomas is still a subject of debate, but most pinealophiles favor restricting the terms pinealoma to neoplasms arising from the pineocytes.